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Rockville, MD, United States

Aparna Biosciences Corporation | Date: 2011-10-18

Chemicals for use in industry and science.

Leng Q.,University of Maryland Baltimore County | Chou S.-T.,University of Maryland Baltimore County | Chou S.-T.,University of Maryland University College | Scaria P.V.,Aparna Biosciences Corporation | And 2 more authors.
Molecular Therapy | Year: 2012

Induction of cytokines by small interfering RNA (siRNA) polyplexes has been a significant concern of researchers attempting to minimize the toxicity of this promising therapy. Although cationic carriers of siRNA are known to increase cytokine levels, few systematic studies have been done to determine what properties of the carrier are important to modulate cytokines. Because branched histidine-lysine (HK) peptides are effective carriers of siRNA and their sequence can be readily modified, we selected this class of carrier to determine which sequences of the peptide were important for cytokine induction. With the use of peripheral blood mononuclear cells (PBMCs), the HK peptide with a higher number of histidines (H3K()4b) in complex with siRNA induced lower levels of cytokines compared with other HK (e.g., H2K4b, H3K4b, H3K(N)4b) siRNA nanoplexes. Notably, these peptides' siRNA polyplexes showed a similar pattern of cytokine induction when injected intravenously in a mouse model, i.e., the HK with higher content of histidines induced cytokines the least. As indicated by the pH-sensitive dye within acidic endosomes, the greater pH-buffering capacity of H3K(H)4b compared with other HK peptides may explain why cytokine levels were reduced. In addition to buffering capacity, the size of HK polyplexes markedly influenced cytokine production. © The American Society of Gene & Cell Therapy.

Scaria P.V.,Aparna Biosciences Corporation | Liu Y.,Aparna Biosciences Corporation | Leng Q.,University of Maryland Baltimore County | Chou S.-T.,University of Maryland Baltimore County | And 3 more authors.
Journal of Drug Targeting | Year: 2014

The treatment of invasive candidiasis associated with growing numbers of immunocompromised patients remains a major challenge complicated by increasing drug resistance. A novel class of branched histidine-lysine (bHK) peptides has promising antifungal activity, and exhibits a mechanism similar to natural histatins, and thus may avoid drug resistance. The present studies evaluate ligand targeting of bHK peptides to fungal surface integrins by determining whether a cyclic RGD (cRGD) peptide with a large PEG linker could enhance bHK peptide antifungal activity. Whereas conjugates containing only the PEG linker reduced bHK peptide activity, conjugates with the cRGD-PEG ligand resulted in marked enhancement of activity against Candida albicans. This study provides the first demonstration of benefit from ligand targeting of antifungal agents to fungal surface receptors. © 2014 Informa UK Ltd. All rights reserved: reproduction in whole or part not permitted.

Chou S.-T.,University of Baltimore | Chou S.-T.,University of Maryland University College | Leng Q.,University of Baltimore | Scaria P.,Aparna Biosciences Corporation | And 2 more authors.
Cancer Gene Therapy | Year: 2011

Our research has focused on systemic delivery of small interference RNA (siRNA) by branched peptides composed of histidine and lysine. After studying several histidine-lysine (HK) peptides, one four-branched peptide, H3K(H)4b, with a predominant repeating pattern of-HHHK-, was found to be an effective carrier of siRNA. Although the unmodified H3K(H)4b carrier of siRNA targeting an oncogene was previously shown to have promise in a tumor-bearing mouse model, we sought to develop a more effective HK carrier of siRNA in this study. Our primary goal was to determine whether different ligand (cyclic RGD)-pegylation patterns on the H3K(H)4b peptide affect siRNA delivery in vitro and in vivo. We compared the unmodified H3K(H)4b with two modified H3K(H)4b peptides for their ability to deliver siRNA in a tumor-bearing mouse model; one modified HK peptide, (RGD-PEG) 4-H3K(H)4b, had four cyclic RGD-polyethylene glycol (cRGD-PEG) conjugates per molecule, whereas the other peptide, (RGD-PEG)-H3K(H)4b, had one cRGD-PEG per molecule. Although the modified HK peptides by themselves did not form stable nanoplexes with siRNA, combination of a highly charged unmodified HK peptide, H2K4b, with either of the modified HK peptides did form stable siRNA nanoparticles. For in vitro experiments with MDA-MB-435 cells that expressed luciferase (Luc), the H3K(H)4b siRNA nanoplexes targeting Luc decreased its activity by 90% compared with negligible downregulation by the modified H3K(H)4b nanoplexes (P>0.01). In contrast, the two modified H3K(H)4b siRNA nanoplexes administered intravenously were more effective than the H3K(H)4b nanoplexes in silencing Luc in a tumor xenograft model. The Luc activity in tumor lysates of mice administered H3K(H)4b, (RGD-PEG)-H3K(H)4b and (RGD-PEG) 4-H3K(H)4b nanoplexes decreased by 18, 35 and 75%, respectively. Thus, the siRNA nanoplex incorporating the highly modified peptide, (RGD-PEG) 4-H3K(H)4b, was the most effective at silencing its target in vivo (P>0.01). These studies demonstrate that selectively modified HK polymers are promising candidates for targeting oncogenes with siRNA. © 2011 Nature America, Inc.

Leng Q.,University of Maryland Baltimore County | Chou S.-T.,University of Maryland Baltimore County | Chou S.-T.,University of Maryland University College | Scaria P.V.,Aparna Biosciences Corporation | And 2 more authors.
Journal of Gene Medicine | Year: 2014

Background: Selecting nonviral carriers for in vivo gene delivery is often dependent on determining the optimal carriers from transfection assays in vitro. The rationale behind this in vitro strategy is to cast a net sufficiently wide to identify the few effective carriers of plasmids for in vivo studies. Nevertheless, many effective in vivo carriers may be overlooked by this strategy because of the marked differences between in vitro and in vivo assays. Methods: After solid-phase synthesis of linear and branched histidine/lysine (HK) peptides, the two peptide carriers were compared for their ability to transfect MDA-MB-435 tumor cells in vitro and then in vivo. Results: By contrast to their transfection activity in vitro, the linear H2K carrier of plasmids was far more effective in vivo compared to the branch H2K4b. Surprisingly, negatively-charged polyplexes formed by the linear H2K peptide gave higher transfection in vivo than did those with a positive surface charge. To examine the distribution of plasmid expression within the tumor from H2K polyplexes, we found widespread expression by immunohistochemical staining. With a fluorescent tdTomato expressing-plasmid, we confirmed a pervasive distribution and gene expression within the tumor mediated by the H2K polyplex. Conclusions: Although mechanisms underlying the efficiency of gene expression are probably multifactorial, unpacking of the H2K polyplex within the tumor appears to have a significant role. Further development of these H2K polyplexes represents an attractive approach for plasmid-based therapies of cancer. © 2014 The Authors. The Journal of Gene Medicine published by John Wiley & Sons, Ltd.

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